Add AVFMT_VARIABLE_FPS to specify which muxers do not need duplicated frames.

Originally committed as revision 17554 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/avformat.h

@@ -265,6 +265,7 @@ typedef struct AVFormatParameters {
 #define AVFMT_NOTIMESTAMPS  0x0080 /**< Format does not need / have any timestamps. */
 #define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
 #define AVFMT_TS_DISCONT    0x0200 /**< Format allows timestamp discontinuities. */
+#define AVFMT_VARIABLE_FPS  0x0400 /**< Format allows variable fps. */
 
 typedef struct AVOutputFormat {
     const char *name;

libavformat/avienc.c

@@ -606,4 +606,5 @@ AVOutputFormat avi_muxer = {
     avi_write_packet,
     avi_write_trailer,
     .codec_tag= (const AVCodecTag* const []){codec_bmp_tags, codec_wav_tags, 0},
+    .flags= AVFMT_VARIABLE_FPS,
 };

libavformat/matroskaenc.c

@@ -909,7 +909,7 @@ AVOutputFormat matroska_muxer = {
     mkv_write_header,
     mkv_write_packet,
     mkv_write_trailer,
-    .flags = AVFMT_GLOBALHEADER,
+    .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,
     .codec_tag = (const AVCodecTag* const []){codec_bmp_tags, codec_wav_tags, 0},
     .subtitle_codec = CODEC_ID_TEXT,
 };

libavformat/movenc.c

@@ -1841,7 +1841,7 @@ AVOutputFormat mov_muxer = {
     mov_write_header,
     mov_write_packet,
     mov_write_trailer,
-    .flags = AVFMT_GLOBALHEADER,
+    .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,
     .codec_tag = (const AVCodecTag* const []){codec_movvideo_tags, codec_movaudio_tags, 0},
 };
 #endif
@@ -1873,7 +1873,7 @@ AVOutputFormat mp4_muxer = {
     mov_write_header,
     mov_write_packet,
     mov_write_trailer,
-    .flags = AVFMT_GLOBALHEADER,
+    .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,
     .codec_tag = (const AVCodecTag* const []){ff_mp4_obj_type, 0},
 };
 #endif

libavformat/nutenc.c

@@ -820,6 +820,6 @@ AVOutputFormat nut_muxer = {
     write_header,
     write_packet,
     write_trailer,
-    .flags = AVFMT_GLOBALHEADER,
+    .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,
     .codec_tag= (const AVCodecTag* const []){codec_bmp_tags, codec_wav_tags, ff_nut_subtitle_tags, 0},
 };